In order to achieve high reliability and redundancy deployment, many enterprise networks and data centers include multiple layer-2 networks located in different geographical locations. These layer-2 networks located in different geographical positions deploy similar businesses, and may achieve layer-2 network interconnection via Ethernet virtual interconnection (EVI) technology, Overlay Transport Virtualization (OTV) technology, and the like. A virtual machine may migrate among the layer-2 networks to achieve dynamic allocation and management of resources among the layer-2 networks.
An Internet user may access an application service provided by a virtual machine in a layer-2 network through an Internet access service provider. However, the user does not perceive the location of the virtual machine providing the application service. Therefore, when the virtual machine migrates from one layer-2 network to another layer-2 network, the IP address of the migrated virtual machine should not change.